﻿<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8" />
    <title>检查当前窗口的状态</title>
    <script>
        function check() {
            if (window.top !== window.self) {
                document.write("<p>这个窗口不是最顶层窗口!我在一个框架?</p>")
            }
            else {
                document.write("<p>这个窗口是最顶层窗口!</p>")
            }
        }
    </script>
</head>
<body>
    <input type="button" onclick="check()" value="检查窗口" />
</body>
</html>